As a Franciscan, I've asked this question many times. Here, at last, are the pope's own words, offered during a talk to the journalist who covered the conclave.Friar Bob

“Some people didn't know why the Bishop of Rome wanted to call himself 'Francis'. Some though of Francis Xavier, Francis de Sales, even Francis of Assisi. I will tell you the story. At the election I had the archbishop emeritus of Sao Paulo next to me. He is also prefect emeritus of the Congregation for the Clergy, Cardinal Claudio Hummes [O.F.M.]: a dear, dear friend. When things were getting a little 'dangerous', he comforted me. And then, when the votes reached the two-thirds, there was the usual applause because the Pope had been elected. He hugged me and said: 'Do not forget the poor.' And that word stuck here [tapping his forehead]; the poor, the poor. Then, immediately in relation to the poor I thought of Francis of Assisi. Then I thought of war, while the voting continued, until all the votes [were counted]. And so the name came to my heart:: Francis of Assisi. For me he is the man of poverty, the man of peace, the man who love and safeguards Creation. In this moment when our relationship with Creation is not so good—right?—He is the man who gives us this spirit of peace, the poor man … Oh, how I wish for a Church that is poor and for the poor!”